Phenotypic and functional analysis of 1,25-dihydroxyvitamin d₃ receptor mediated modulation of the human myeloma cell line rpmi 8226

Several recent studies have demonstrated the presence of specific receptors for the 1,25-dihydroxyvitamin D₃ (calcitriol) in activated normal lymphocytes. By DNA cellulose chromatography, we show evidence of such specific receptors in the human myeloma cell line RPMI 8226. Nanomolar concentrations of 1,25-dihydroxyvitamin D₃ reduce the proliferation of RPMI 8226 cells significantly and simultaneously induce the appearance of both new properties and phenotype expression, such as butyrate esterase, enhanced expression of CD20 (Bl), CD15 (Leu-Ml) antigens and X chains, and decreased expression of the PCI antigen using microfluorometric analysis. But such an increased expression of membrane X chains was not associated with an enhanced secretion of X chains. Furthermore, the bone resorbing activity produced normally by RPMI 8226 cells was reduced significantly after 1,25-dihydroxyvitamin D3 treatment. The possible mechanisms and significance of these new functional and phenotypic properties are discussed with respect to the B-cell lineage.